Sealing devices

ABSTRACT

A fluid seal for a disc valve or the like wherein a resilient seal is confined within a circumferential recess in the valve body which has a projecting ledge on at least one side of said recess. At lease one gib strip is positioned between the seal and the projecting ledge. One side of the gib strip has a stepped portion to present a projecting ledge whereby the strip and seal are retained resiliently between the side wall of the recess and the resilient seal. A second embodiment discloses the use of the gib strips and corresponding ledges on each side of the resilient seal.

United States Patent Lambie 1 51 Sept. 26, 1972 [54] SEALING DEVICES[72] Inventor: John Walkinshaw Lambie, 13 Culin Place, Kilmarnock,Ayrshire, Scotland [22] Filed: Oct. 26,1970

[2]] Appl. No.: 83,829

[30] Foreign Appllcatlon Prlorlty Data Oct. 25, 1969 Great Britain..52,388/69 [52] Cl. ..277/l88, 277/166, 277/187, 277/207 [51] Int. Cl...Fl6j 15/00, F16j 15/32 [58] Field of Search ..277/188, 166, 167, 207,187,

[56] References Cited UNITED STATES PATENTS 2,665,461 1/1954 Rodgers..277/1s7 Duval ..277/1 87 FOREIGN PATENTS OR APPLICATIONS 5,549 3/1905Great Britain ..277/166 Primary Examiner-Houston S. Bell, Jr.Attorney-George S. Schwind [57] ABSTRACT A fluid seal for a disc valveor the like wherein a resilient seal is confined within acircumferential recess in the valve body which has a projecting ledge onat least one side of said recess. At lease one gib strip is positionedbetween the seal and the projecting ledge. One side of the gib strip hasa stepped portion 'to present a projecting ledge whereby the strip andseal are retained resiliently between the side wall of the recess andthe resilient seal. A second embodiment discloses the use of the gibstrips and corresponding ledges on each side of the resilient seal.

6 Claims, 5 Drawing Figures 1 SEALING DEVICES This invention relates toa fluid seal of the type intended to prevent leakage of fluid through aclearance gap.

The device is applicable to a continuous seal, e.g. a ring sealemploying an O-ring, and to a linear seal, e.g. on the face of a dockgate.

Seals as at present known employing separate sealing strips located ingrooves suffer from certain disadvantages. A sealing strip which is tobe used in a position where the clearance gap between the surfaces to besealed is large tends to be forced by the pressure of the fluid againstwhich the seal operates out of the groove containing it and to beextruded through the clearance gap. A similar effect is often found tooccur in situations where the sealing strip requires to be brought outof contact with the other sealing surface, an example being the faceseal on a valve obturator disc. In such a situation the flow of fluid athigh velocity passing over the sealing strip, usually an O-ring, and theface with which the O-ring is normally engageable causes a venturieffect over the projecting curved portion of the O-ring and the pressuredifferential then tends to lift the O-ring out of its groove. Variousproposals have been made to overcome this difficulty.

For example the groove may be undercut so that the side faces are formedwith overhanging shoulders projecting towards one another, the ring whenbeing put in place being forced into the groove so that a portion of itextends below and expands into the undercut. In another construction oneside wall of the groove is inclined to provide an overhang and a keeperring having a tapered side face inclined tov provide an overhang isinserted into the groove after the ring has been placed in position sothat the sealing ring is held in a groove of dove-tailed cross section.Both these constructions suffer from their own particular disadvantages.In the construction employing the groove formed with the overhangingshoulders the ring is difficult to insert without damaging it and isalso difficult to remove when it has to be replaced, while theconstruction employing the keeper ring requires a large face to hold theseal because the keeper ring requires some form of fixing e.g. screws tohold it in place.

It is an object of the present invention to provide a fluid seal whichis easy and cheap to provide, which requires little more room than thesimplest type of O- ring, and which incorporates a sealing strip whichcan be fitted easily and without damage and can be removed comparativelyeasily.

According to the present invention a fluid seal for sealing a gapbetween the juxtaposed faces of two elements incorporates the featuresthat the face of one element is formed with a groove both side walls ofwhich are undercut to overhang the bottom of the groove, at least one ofthe undercuts being in the form of a shoulder, a resilient sealing striprests in the groove, and at least one gib strip having one side facestepped to present a projecting ledge and the other side face slopedinwards to form an overhang is contained in the groove with the ledge onthe gib strip engaging under the shoulder in the side wall of the grooveand being held then by the resilient thrust of the sealing strip, thesealing strip being retained in the groove by the gib strip.

In certain applications particularly where sealing strips of large crosssection are to be employed it may be convenient to provide two gibstrips, both side walls of the groove being undercut to presentshoulders, the gib strips being opposite handed in cross section so thatwhen the fluid seal is assembled the sealing strip is held between thetwo gib strips the ledges of which are engaged with the respectiveshoulders in the groove.

The arrangement described is applicable to aface seal i.e. a seal formedon a planar face. This type of seal is particularly of use in connectionwith pump valves. In this application the seal is usually annular inform, the gib strip and the sealing strip being correspondingly shaped.

Another use for a face seal is in sealing the gate of a gate valve. Thegroove may be continuous and rectangular in plan, the corners beingformed as curves.

The seal is applicable also to cylindrical surfaces and may be formed asan external or an internal seal i.e. the groove may be formed on theexternal cylindrical surface of a cylindrical object, or on the innercylindrical face of a hollow object formed with a bore, the groove beingan annular groove and the gib strip and the sealing strip being rings.

The gib strip may be of metal or of a hard non-metallic substance, e.g.a hard plastics material. A suitable substance with an application to awide variety of conditions is P.T.F.E.

The accompanying drawings illustrate various types of known seals andseals according to the invention. In particular,

FIG. I is a cross section of an ordinary O-ring seal,

FIG. 2 a cross section of a seal in which the side faces of the groovesare undercut whereby to trap the sealing ring in place,

FIG. 3 is a cross section of a' seal employing a keeper ring held inplace by set screws,

FIG. 4 is a cross section of a seal according to the invention employingone gib strip and FIG. 5 is a cross section of a seal according to theinvention employing two gib strips.

As the constructions of FIGS. 1, 2 and 3 are already well known only theconstructions according to the invention and as illustrated in FIG. 4and 5 will be described.

In FIG. 4, 1 denotes one element the face 2 of which is formed with agroove 3 both side walls 4 and 5 of which are undercut to overhang thebottom 6 of the groove 3. The undercut in the wall 5 is in the form of ashoulder 7. 8 denotes a sealing strip resting in the groove 3 and 9denotes a gib strip having one side face 10 stepped to present aprojecting ledge 11 and the other side face 12 sloping inwards. Thesealing strip 8 in trying to regain its undistorted shape pressesagainst the side face 12 of the gib strip 9 and holds the projectingledge 11 thereon in engagement with the shoulder 7 so that the gib strip9 cannot come out while the overhang of the side wall 4 of the groove 3and of the side face 12 of the gib strip 9 hold the sealing strip 8 inplace. The construction of FIG. 5 differs from that of FIG. 4 only inthat it employs two gib strips, both side walls 4 and 5 of the groove 3being accordingly undercut and the gib strips 9 being opposite-handed.

In practice and referring to FIGS. 4 and 5, a seal is made by insertingthe sealing strip 8 into the groove 3 in the element 1 and then pressingthe gib strip 9 into place. The gib strip 9 compresses the sealing strip8 as it moves into the groove 3 and the transverse resilient thrust ofthe sealing strip 8 then causes the ledge 11 on the gib strip 9-toengage under the shoulder 7 in the groove 3 thereby locking both the gibstrip 9 and the the gib strip engaging under the shoulder in the sidewall of the groove and being held then by the resilient sealing strip 8in place. In such a seal a small portion of v the sealing strip 8protrudes from the groove and provides the sealing action while thesealing strip is gripped tightly enough to prevent ingress of fluidunder pressure down the side face of the strip. It is such ingress offluid which causes the extrusion or the lifting of a sealing strip suchas that illustrated in FIG. 1 in conditions where the juxtaposed faceshave been moved just far enough apart to cause the seal to be broken. Asthe ledge 11 on the gib strip 9 and the shoulder 7 in the groove 3 canbe small-in widthin proportion to the width of the groove 3 it has beenfound that the gib strip 9 is easily inserted in place and the sealtakes up little more room than an ordinary O-ring seal using a groove ofrectangular section such as is illustrated in FIG. 1. It may be foundconvenient for assembly purposes in annular seals to form the gib strip9 as a discontinuous ring. This is not a disadvantage, however, becausethe ends'lie in abutting relationship when the ring is in place and inany event, the gib ring may be placed on the higher pressure side of theseal so that the effect of the extremely small gap between the abuttingends of the strip forming the gib ring does not cause any leakagethrough the seal.

What we claim is:

l. A fluid seal for sealing a gap between the juxtaposed faces of twoelements incorporating the features that the face of one element isformed with a groove both side walls of which are undercut to overhangthe bottom of the groove, at least one of the undercuts being in theform of a shoulder, a resilient sealing strip rests in the groove, andat least one gib strip having one side face stepped to present aprojecting ledge and the other side face sloped inwards to form anoverhang is contained in the groove with the ledge on thrust of thesealing strip, the sealing strip being retained in the groove by the gibstrip.

2. A fluid seal as claimed in claim I incorporating two gib strips, bothside walls of the groove being undercut to present shoulders, the gibstrips being opposite handed in cross section so that when the fluidseal is assembled the sealing strip is held between the two gib stripsthe ledges of which are engaged with the respective shoulders in thegroove.

3. A fluid seal as claimed in claim 1 in which the face formed with thegroove is a planar face, the groove being a continuous groove in saidface the gib strip and the sealing strip being correspondingly shaped.

4. A fluid seal as claimed in claim 3 in which the groove is rectangularin plan, the corners being formed as curves.

5. A fluid seal as claimed in claim 1 in the face formed with the grooveis a cylindrical face, the groove being an annular groove, the gib stripand the sealing strip being rings.

6. A fluid seal for sealing a gap between the juxta ose face of tw elemets he ace of one e ement l iavmg therein a groove with a pair of opposedside walls, both of which are undercut to overhang the bottom of thegroove,

one undercut being constituted as a lateralshoulder,

a resilient sealing strip seated in the groove,

a gib strip seated in the groove between the sealing strip and theshouldered wall of the groove and having a side face stepped to presenta lateral ledge engaged beneath said groove wall shoulder,

the other side face of the gib strip having an overhang compressing thesealing strip inwardly in the groove and laterally toward said shoulder,thereby holding the ledge locked beneath the shoulder,

the sealing strip being held in the groove by the gib strip when itsledge is engaged beneath said groove wall shoulder.

1. A fluid seal for sealing a gap between the juxtaposed faces of twoelements incorporating the features that the face of one element isformed with a groove both side walls of which are undercut to overhangthe bottom of the groove, at least one of the undercuts being in theform of a shoulder, a resilient sealing strip rests in the groove, andat least one gib strip having one side face stepped to present aprojecting ledge and the other side face sloped inwards to form anoverhang is contained in the groove with the ledge on the gib stripengaging under the shoulder in the side wall of the groove and beingheld then by the resilient thrust of the sealing strip, the sealingstrip being retained in the groove by the gib strip.
 2. A fluid seal asclaimed in claim 1 incorporating two gib strips, both side walls of thegroove being undercut to present shoulders, the gib strips beingopposite handed in cross section so that when the fluid seal isassembled the sealing strip is held between the two gib strips theledges of which are engaged with the respective shoulders in the groove.3. A fluid seal as claimed in claim 1 in which the face formed with thegroove is a planar face, the groove being a continuous groove in saidface the gib strip and the sealing strip being correspondingly shaped.4. A fluid seal as claimed in claim 3 in which the groove is rectangularin plan, the corners being formed as curves.
 5. A fluid seal as claimedin claim 1 in the face formed with the groove is a cylindrical face, thegroove being an annular groove, the gib strip and the sealing stripbeing rings.
 6. A fluid seal for sealing a gap between the juxtaposedfaces of two elements, the face of one element having therein a groovewith a pair of opposed side walls, both of which are undercut tooverhang the bottom of the groove, one undercut being constituted as alateral shoulder, a resilient sealing strip seated in the groove, a gibstrip seated in the groove between the sealing strip and the shoulderedwall of the groove and having a side face stepped to present a lateralledge engaged beneath said groove wall shoulder, the other side face ofthe gib strip having an over-hang compressing the sealing strip inwardlyin the groove and laterally toward said shoulder, thereby holding theledge locked beneath the shoulder, the sealing strip being held in thegroove by the gib strip when its ledge is engaged beneath said groovewall shoulder.